Magnetic Heat Pump Apparatus

ABSTRACT

Provided is a magnetic heat pump apparatus which solves a problem caused by the use of a rotary valve and which has improved efficiency. The magnetic heat pump apparatus includes magnetic working bodies 11A and 11B, which are provided with magnetic working substances 13 having a magnetocaloric effect and in which a heat transfer medium is circulated, permanent magnets 6 which change the size of a magnetic field to be applied to the magnetic working substances, displacers 8 which cause the heat transfer medium to reciprocate between a high-temperature end 14 and a low-temperature end 16 of each of the magnetic working bodies, and external heat transfer medium circulation circuits 27 and 28 which have external heat exchangers 19 and 22 and which circulate a second heat transfer medium. The external heat transfer medium circulation circuits cause heat exchange to be carried out between the second heat transfer medium and the heat transfer medium of each of the magnetic working bodies, and then circulate the second heat transfer medium which has been subjected to the heat exchange to external heat exchangers.

TECHNICAL FIELD

The present invention relates to a magnetic heat pump apparatus utilizing the magnetocaloric effect of magnetic working substances.

BACKGROUND ART

Recently, in place of a conventional vapor compression refrigeration apparatus using a gas refrigerant, such as chlorofluorocarbon, a magnetic heat pump apparatus utilizing the property of magnetic working substances that causes a large temperature change at magnetization and demagnetization (magnetocaloric effect) has been receiving attention.

Heretofore, a magnetic heat pump apparatus of this type having magnetic working substances filled in the ducts of magnetic working bodies changes a magnetic field to be applied to the magnetic working substances by causing permanent magnets to come in contact with or separate from the magnetic working bodies. At this time, when the magnetic field to be applied is increased (magnetized), the temperature of the magnetic working substances increases, and when the magnetic field is decreased (demagnetized), the temperature decreases.

Meanwhile, a heat transfer medium (water or the like) is reciprocated between a high-temperature end and a low-temperature end of the magnetic working bodies by using a pump and a rotary valve. In this case, the magnetic working substances are magnetized to increase the temperature thereof, and then the heat transfer medium is moved to the high-temperature end side from the low-temperature end side, whereby heat is exchanged between the magnetic working substances in which the temperature has increased by the magnetization and the low-temperature heat transfer medium. Thus, a temperature gradient in which the temperature is high on the high-temperature end side and the temperature is low on the low-temperature end side arises in the magnetic working bodies.

Next, when the magnetic working substances are demagnetized, the temperature decreases. The heat transfer medium is moved to the low-temperature end side from the high-temperature end side, whereby heat is exchanged between the magnetic working substances in which the temperature has decreased by the demagnetization and the high-temperature heat transfer medium. This further increases the temperature gradient of the magnetic working bodies.

Thus, the temperature change caused by the magnetocaloric effect is stored in the magnetic working bodies themselves, and the heat transfer medium on the low-temperature end side and the heat transfer medium on the high-temperature end side are taken out to an external heat exchanger, whereby heat absorption (refrigerating) or heat dissipation (heating) is carried out (refer to, for example, Patent Document 1).

CITATION LIST Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2008-51409 SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, the use of a rotary valve gives rise to a mixing loss or frictional heat of heat transfer media having different temperatures due to structural reasons. There has been another problem in that the flow rate of a heat transfer medium differs between an external heat exchanger and a magnetic working body.

The present invention has been made with a view toward solving the technical problems with the prior art described above, and an object of the invention is to provide a magnetic heat pump apparatus which solves the problem caused by the use of a rotary valve, thereby improving efficiency.

Means for Solving the Problems

A magnetic heat pump apparatus in accordance with the present invention includes: a magnetic working body which has a magnetic working substance having a magnetocaloric effect and in which a heat transfer medium is circulated; a magnetic field changing device which changes the size of a magnetic field to be applied to the magnetic working substance; a displacer which reciprocates the heat transfer medium between a high-temperature end and a low-temperature end of the magnetic working body; and an external heat transfer medium circulation circuit which has an external heat exchanger and which circulates a second heat transfer medium, wherein the external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium of the magnetic working body to exchange heat, and circulates the second heat transfer medium that has been subjected to the heat exchange to the external heat exchanger.

The magnetic heat pump apparatus according to the present invention of claim 2 includes: a first external heat transfer medium circulation circuit which has an external heat exchanger on a heat dissipation side; and a second external heat transfer medium circulation circuit which has an external heat exchanger on a heat absorption side, wherein the first external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium on a high-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium subjected to the heat exchange to the external heat exchanger on the heat dissipation side, and the second external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium on a low-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium subjected to the heat exchange to the external heat exchanger on the heat absorption side in the foregoing invention.

The magnetic heat pump apparatus according to the invention of claim 3 includes: a high-temperature end side displacer provided on the high-temperature end side of the magnetic working body; and a low-temperature end side displacer provided on the low-temperature end side of the magnetic working body, wherein the high-temperature end side displacer and the low-temperature end side displacer are placed back to back in the foregoing inventions.

Advantageous Effect of the Invention

The magnetic heat pump apparatus according to the present invention includes a magnetic working body which has a magnetic working substance having a magnetocaloric effect and in which a heat transfer medium is circulated, a magnetic field changing device which changes the size of a magnetic field to be applied to the magnetic working substance; a displacer which reciprocates the heat transfer medium between a high-temperature end and a low-temperature end of the magnetic working body; and an external heat transfer medium circulation circuit which has an external heat exchanger and which circulates a second heat transfer medium, wherein the external heat transfer medium circulation circuit causes heat exchange between the second heat transfer medium and the heat transfer medium of the magnetic working body, and circulates the second heat transfer medium that has been subjected to the heat exchange to the external heat exchanger. Thus, the heat exchange can be carried out between the heat transfer media on the high-temperature end side and the low-temperature end side of the magnetic working body and the second heat transfer medium thereby to indirectly take out the obtained heat transfer medium into an external heat exchanger.

Further, the heat transfer medium of the magnetic working body is reciprocated by the displacer, so that the problem of the mixing loss or the frictional heat, which would be caused by the use of a rotary valve, can be solved, and the temperature change caused by the magnetocaloric effect of the magnetic working substances can be effectively and efficiently utilized.

In this case, as with the invention of claim 2, if a first external heat transfer medium circulation circuit, which has an external heat exchanger on a heat dissipation side, and a second external heat transfer medium circulation circuit, which has an external heat exchanger on a heat absorption side, are provided, and if the first external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium on a high-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium that has been subjected to the heat exchange to the external heat exchanger on the heat dissipation side, and the second external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium on a low-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium that has been subjected to the heat exchange to the external heat exchanger on the heat absorption side, then the temperature of the heat transfer medium on the high-temperature end side of the magnetic working body can be efficiently moved to the second heat transfer medium, and the heat of the second heat transfer medium can be efficiently moved to the heat transfer medium on the low-temperature end side.

Further, the driving power of the displacers can be controlled to a minimum by placing, back to back, the high-temperature end side displacer provided on the high-temperature end side of the magnetic working body and the low-temperature end side displacer provided on the low-temperature end side of the magnetic working body, as with the invention of claim 3.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall configuration diagram of a magnetic heat pump apparatus of an example to which the present invention has been applied;

FIG. 2 is a sectional view of an AMR (Active Magnetic Regenerator) for the magnetic heat pump of FIG. 1; and

FIG. 3 is an overall configuration diagram for explaining a magnetic heat pump apparatus of another example to which the present invention has been applied.

MODE FOR CARRYING OUT THE INVENTION

The following will describe an example of the present invention with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a magnetic heat pump apparatus 1 of the example to which the present invention has been applied, and FIG. 2 is a sectional view of a magnetic heat pump AMR 2 of the magnetic heat pump apparatus 1.

(1) Configuration of the Magnetic Heat Pump Apparatus 1

First, the magnetic heat pump AMR 2 of FIG. 2 will be described. The magnetic heat pump AMR 2 of the magnetic heat pump apparatus 1 is provided with a hollow cylindrical housing 3, both ends in the axial direction of which are closed and the interior of which is in a vacuum-tight state, and a rotating body 7 which is located at the axial center in the housing 3 and in which a pair (two pieces) of permanent magnets 6 (magnetic field generating members) are radially attached to axisymmetric peripheral surfaces. Both ends of a shaft of the rotating body 7 are rotatably and pivotably supported by the housing 3, and the rotating body 7 is coupled to a rotating shaft 10 of a motor M (FIG. 1, a servo motor) through a decelerator, which is not illustrated, and the rotation is controlled by the motor M. The rotating body 7, the permanent magnets 6, the motor M, and the like constitute a magnetic field changing device, which changes the size of a magnetic field to be applied to magnetic working substances 13 described later. Further, cams 9 (FIG. 1) that drive displacers (pistons) 8, which will be described later, are also coupled to the rotating shaft 10 of the motor M.

Meanwhile, four magnetic working bodies 11A, 11A, 11B, and 11B, which are twice the number of the permanent magnets 6, are fixed to the inner periphery of the housing 3 at equal intervals in the circumferential direction near the outer peripheral surface of the permanent magnets 6. In the case of the example, the magnetic working bodies 11A and 11A are disposed at axisymmetric positions with the rotating body 7 interposed therebetween, and the magnetic working bodies 11B and 11B are disposed at axisymmetric positions with the rotating body 7 interposed therebetween (FIG. 2). The magnetic working bodies 11A and 11B are those in which magnetic working substances 13 having a magnetocaloric effect are individually charged into a hollow duct 12 having a circular arc shaped cross section along the inner periphery of the housing 3 such that a heat transfer medium (herein water: a first heat transfer medium) can circulate (FIG. 1).

Although the magnetic working bodies 11A and 11B are actually disposed two each at the axisymmetric positions as illustrated in FIG. 2, FIG. 1 representatively illustrates one magnetic working body 11A and one magnetic working body 11B. In the example, the duct 12 is composed of a resin material having a high heat insulation property. Thus, the loss of heat into the atmosphere (outside) from the magnetic working substances 13 in which the temperature increases or decreases due to the change (magnetization and demagnetization) of the magnetic field as described later is reduced. In the example, an Mn-based material or an La-based material is used as the magnetic working substances 13.

Further, in the overall configuration diagram of the magnetic heat pump apparatus 1 of FIG. 1 in which the magnetic heat pump AMR 2 is installed, each of the magnetic working bodies 11A and 11B has a high-temperature end 14 at one end (the right end in FIG. 1) and has a low-temperature end 16 at the other end (the left end in FIG. 1). Further, a high-temperature pipe 17 is attached to the high-temperature end 14 of each of the magnetic working bodies 11A, 11A, 11B, and 11B (FIG. 1 representatively illustrates one magnetic working body 11A and one magnetic working body 11B) and is led out from the housing 3 of FIG. 2. Further, a low-temperature pipe 18 is attached to the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B (FIG. 1 representatively illustrates one magnetic working body 11A and one magnetic working body 11B) and is led out from the housing 3 of FIG. 2.

Connected to the high-temperature pipe 17 are high-temperature end side heat exchangers 24 and 24 disposed in the high-temperature end 14 of each of the magnetic working bodies 11A, 11A, 11B and 11B, and an external heat exchanger 19 on the heat dissipation side disposed outside the magnetic heat pump AMR 2. Further, a circulation pump 21 is provided in the high-temperature pipe 17. A second heat transfer medium (this being also water) is sealed in the high-temperature pipe 17. The second heat transfer medium is circulated by the circulation pump 21 through the heat exchanger 24 provided in the high-temperature end 14 of each of the magnetic working bodies 11A, 11A, the external heat exchanger 19, and the heat exchanger 24 provided in the high-temperature end 14 of each of the magnetic working bodies 11B and 11B in this order. The second heat transfer medium is subjected to heat exchange with the heat transfer medium on the high-temperature end 14 side (the first heat transfer medium) of each of the magnetic working bodies 11A, 11A, 11B and 11B in the heat exchangers 24 and 24. The high-temperature pipe 17, the heat exchangers 24 and 24, the external heat exchanger 19, and the circulation pump 21 constitute a first external heat transfer medium circulation circuit 27.

Connected to the low-temperature pipe 18 are low-temperature end side heat exchangers 26 and 26 disposed in the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B and 11B, and a heat absorption side external heat exchanger 22 disposed outside the magnetic heat pump AMR 2. Further, a circulation pump 23 is provided in the low-temperature pipe 18. The second heat transfer medium is sealed also in the low-temperature pipe 18. The second heat transfer medium is circulated by the circulation pump 23 through the heat exchanger 26 provided in the low-temperature end 16 of each of the magnetic working bodies 11A and 11A, the external heat exchanger 22, and the heat exchanger 26 provided in the low-temperature end 16 of each of the magnetic working bodies 11B and 11B in this order. The second heat transfer medium is subjected to heat exchange with the heat transfer medium on the low-temperature end 16 side (the first heat transfer medium) of each of the magnetic working bodies 11A, 11A, 11B and 11B in the heat exchangers 26 and 26. The low-temperature pipe 18, the heat exchangers 26 and 26, the external heat exchanger 22, and the circulation pump 23 constitute a second external heat transfer medium circulation circuit 28.

The displacers (pistons) 8 are individually disposed at the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B, and are driven by the cams 9 rotated by the rotating shaft 10 of the motor M to cause the heat transfer medium (water: the first heat transfer medium) to reciprocate between the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B.

More specifically, when the displacer 8 on the high-temperature end 14 side of each of the magnetic working bodies 11A and 11A retreats and the displacer 8 on the low-temperature end 16 side thereof advances as illustrated in FIG. 1, the heat transfer medium is moved to the high-temperature end 14 side from the low-temperature end 16 side of the magnetic working body 11A. On the other hand, the displacer 8 on the low-temperature end 16 side of each of the magnetic working bodies 11B and 11B retreats and the displacer 8 on the high-temperature end 14 side thereof advances as illustrated in FIG. 1, so that the heat transfer medium is moved to the low-temperature end 16 side from the high-temperature end 14 side of the magnetic working body 11B. The displacers 8 and the cams 9 and further the motor M, the rotating shaft 10, and the like constitute a heat transfer medium moving device that causes the heat transfer medium to reciprocate between the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B.

(2) Operation of the Magnetic Heat Pump Apparatus 1

The operation of the magnetic heat pump apparatus 1 of the above-described configuration will be described. First, when the rotating body 7 is located at the position of 0° (position illustrated in FIG. 2), the permanent magnets 6 and 6 are located at the positions of 0° and 180°. Therefore, the size of magnetic fields to be applied to the magnetic working substances 13 of the magnetic working bodies 11A and 11A at the positions of 0° and 180° increases and the temperature increases by magnetization. On the other hand, the size of magnetic fields to be applied to the magnetic working substances 13 of the magnetic working bodies 11B and 11B located at the positions of 90° and 270°, the phases of which differ therefrom by 90° decreases and the temperature decreases by demagnetization.

When the rotating body 7 is located at the position of 0° (FIG. 2) by the rotation of the motor M, the cams 9 and 9 are driven by the rotating shaft 10 of the motor M to retreat the displacers 8 on the high-temperature end 14 sides of the magnetic working bodies 11A and 11A and advance the displacers 8 on the low-temperature end 16 sides thereof as illustrated in FIG. 1. Thus, the heat transfer medium is moved to the high-temperature end 14 side from the low-temperature end 16 side of the magnetic working body 11A.

Thus, heat is exchanged between the magnetic working substances 13 of the magnetic working bodies 11A and 11A in which the temperature has increased by magnetization by the permanent magnets 6 and 6 and the low-temperature heat transfer medium thereby to produce a temperature gradient in which the temperature on the high-temperature end 14 side is high and the temperature on the low-temperature end 16 side is low in each of the magnetic working bodies 11A and 11A.

When the rotating body 7 is located at the position of 0° (FIG. 2) by the rotation of the motor M, the cams 9 and 9 are driven by the rotating shaft 10 of the motor M to advance the displacers 8 on the high-temperature end 14 sides of the magnetic working bodies 11B and 11B and retreat the displacers 8 on the low-temperature end 16 sides thereof as illustrated in FIG. 1. Thus, the heat transfer medium is moved to the low-temperature end 16 side from the high-temperature end 14 side of the magnetic working body 11B. Thus, heat is exchanged between the magnetic working substances 13 of the magnetic working bodies 11B and 11B, in which the temperature has decreased by demagnetization, and the high-temperature heat transfer medium to further increase the temperature gradients of the magnetic working bodies 11B and 11B.

Next, when the rotating body 7 is rotated by 90° by the motor M, the permanent magnets 6 and 6 are brought to the positions of 90° and 270°. Therefore, the size of magnetic fields to be applied to the magnetic working substances 13 of the magnetic working bodies 11B and 11B located at the positions of 90° and 270° increases and the temperature increases by magnetization. On the other hand, the size of magnetic fields to be applied to the magnetic working substances 13 of the magnetic working bodies 11A and 11A located at the positions of 0° and 180°, the phases of which differ therefrom by 90° decreases and the temperature decreases by demagnetization.

When the rotating body 7 is located at the position of 90° by the rotation of the motor M, the cams 9 and 9 are driven by the rotating shaft 10 of the motor M to advance the displacers 8 on the high-temperature end 14 sides of the magnetic working bodies 11A and 11A and retreat the displacers 8 on the low-temperature end 16 sides thereof. Thus, the heat transfer medium is moved to the low-temperature end 16 side from the high-temperature end 14 side of the magnetic working body 11A. Thus, heat is exchanged between the magnetic working substances 13 of the magnetic working bodies 11A and 11A, in which the temperature has decreased by demagnetization, and the high-temperature heat transfer medium to further increase the temperature gradients of the magnetic working bodies 11A and 11A.

When the rotating body 7 is brought to the position of 90° by the rotation of the motor M, the cams 9 and 9 are driven by the rotating shaft 10 of the motor M to advance the displacers 8 on the low-temperature end 16 sides of the magnetic working bodies 11B and 11B and retreat the displacers 8 on the high-temperature end 14 sides thereof. Thus, the heat transfer medium is moved to the high-temperature end 14 side from the low-temperature end 16 side of the magnetic working body 11B.

Thus, heat is exchanged between the magnetic working substances 13 of the magnetic working bodies 11B and 11B, in which the temperature has increased by magnetization by the permanent magnets 6 and 6, and the low-temperature heat transfer medium to further increase the temperature gradients of the magnetic working bodies 11B and 11B.

Thus, the heat transfer medium on the high-temperature end 14 side of each of the magnetic working bodies 11A, 11A, 11B, and 11B, in which the temperature has increased as described above, exchanges heat with the second heat transfer medium of the first external heat transfer medium circulation circuit 27 in the heat exchanger 24, and the temperature of the second heat transfer medium increases. The second heat transfer medium, the temperature of which has increased, is circulated to the heat exchanger 19 on the heat dissipation side through the high-temperature pipe 17 by the circulation pump 21, dissipating heat to the outside.

The heat transfer medium on the low-temperature end 16 side of each of the magnetic working bodies 11A, 11A, 11B, and 11B in which the temperature has decreased exchanges heat with the second heat transfer medium of the second external heat transfer medium circulation circuit 28 in the heat exchanger 26, and the temperature of the second heat transfer medium decreases. The second heat transfer medium with the decreased temperature is circulated to the heat absorption side external heat exchanger 22 through the low-temperature pipe 18 by the circulation pump 23, absorbing heat from the outside. As the heat transfer medium (the first heat transfer medium) reciprocates, temperature changes in synchronization with the reciprocation are observed at the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A and 11B. However, the heat exchange with the second heat transfer medium is carried out as described above, and the heat is dissipated or absorbed in the external heat exchanger 19 or 22, thereby leveling the temperature changes of the heat transfer medium (the first heat transfer medium).

The rotation of the rotating body 7 by the motor M and the switching of the displacers 8 are carried out at relatively high speeds and relatively rapid timings, the heat transfer medium (water) is reciprocated between the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B, and the heat absorption into and the heat dissipation from the magnetic working substances 13 of each of the magnetic working bodies 11A, 11A, 11B, and 11B to be magnetized and demagnetized are repeated, whereby a temperature difference between the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B gradually increases. Then, the temperature of the low-temperature end 16 of each of the magnetic working bodies 11A, 11A, 11B, and 11B provided with the heat exchanger 26, through which the second heat transfer medium to be circulated to the heat absorption side external heat exchanger 22 passes, eventually decreases to a temperature at which the refrigerating capacity of the magnetic working substances 13 and a heat load of an object to be cooled by the external heat exchanger 22 are balanced, and the temperature of the high-temperature end 14 of each of the magnetic working bodies 11A, 11A, 11B, and 11B provided with the heat exchanger 24, through which the second heat transfer medium to be circulated to the external heat exchanger 19 on the heat dissipation side passes, becomes a substantially constant temperature because the heat dissipation capacity and the refrigerating capacity of the external heat exchanger 19 are brought into balance.

As described above, according to the present invention, the heat transfer medium is reciprocated between the high-temperature end 14 and the low-temperature end 16 of each of the magnetic working bodies 11A and 11B by the displacers 8, the external heat transfer medium circulation circuits 27 and 28, which circulate the second heat transfer medium to the external heat exchangers 19 and 22, are provided, the heat exchange is carried out between the second heat transfer medium and the heat transfer media of the magnetic working bodies 11A and 11B by the external heat transfer medium circulation circuits 27 and 28, and the second heat transfer medium which has been subjected to the heat exchange is circulated to the external heat exchangers 19 and 22. Therefore, the heat exchange can be carried out between the heat transfer medium (the first heat transfer medium) on the high-temperature end 14 side and the low-temperature end 16 side of each of the magnetic working bodies 11A and 11B and the second heat transfer medium, and the heat transfer medium after the heat exchange can be indirectly taken out to the external heat exchangers 19 and 22.

Further, the heat transfer media of the magnetic working bodies 11A and 11B are reciprocated by the displacers 8, so that the problem of the mixing loss or the frictional heat, which would arise due to the use of a rotary valve were used, is solved. Thus, the present invention makes it possible to effectively and efficiently utilize the temperature changes caused by the magnetocaloric effect of the magnetic working substances 13.

Further, in the example, the first external heat transfer medium circulation circuit 27 having the heat dissipation side external heat exchanger 19 and the second external heat transfer medium circulation circuit 28 having the heat absorption side external heat exchanger 22 are provided, the first external heat transfer medium circulation circuit 27 causes heat exchange to be carried out between the second heat transfer medium and the heat transfer medium (the first heat transfer medium) on the high-temperature end 14 side of each of the magnetic working bodies 11A and 11B, the second heat transfer medium which has been subjected to the heat exchange is circulated to the heat dissipation side external heat exchanger 19, the second external heat transfer medium circulation circuit 28 causes heat exchange to be carried out between the second heat transfer medium and the heat transfer medium (the first heat transfer medium) on the low-temperature end 16 side of each of the magnetic working bodies 11A and 11B, and the second heat transfer medium which has been subjected to the heat exchange is circulated to the heat absorption side external heat exchanger 22. This arrangement makes it possible to efficiently move the temperature of the heat transfer medium (the first heat transfer medium) on the high-temperature end 14 side of each of the magnetic working bodies 11A and 11B to the second heat transfer medium, and to efficiently move the heat of the second heat transfer medium to the heat transfer medium (the first heat transfer medium) on the low-temperature end 16 side.

In the example, the displacers 8 and the cams 9 of the magnetic working bodies 11A and 11B are driven at the high-temperature end 14 side and the low-temperature end 16 side, respectively, as illustrated in FIG. 1. Alternatively, however, the displacers 8 provided on the high-temperature end 14 side (the displacers on the high-temperature end side) of the magnetic working bodies 11A and 11B and the displacers 8 provided on the low-temperature end 16 side (the displacers on the low-temperature end side) thereof could be placed back to back. In such a case, it would be necessary to change the shapes of the magnetic working bodies 11A and 11B to circular shapes or the like, and the specific configuration of the magnetic heat pump AMR 2 would be different from that of FIG. 2. However, the cam 9 on the high-temperature end 14 side and the cam 9 on the low-temperature end 16 side could be combined into one piece, and the displacer 8 on the high-temperature end 14 side could be advanced/retreated at both sides thereof so as to advance/retreat the displacer 8 on the low-temperature end 16 side, as indicated by the dashed line arrows F1 and F2 in FIG. 3. Therefore, the cam 9 could be shared and the driving power for driving the displacers 8 could be controlled to a minimum.

The overall configuration of the magnetic heat pump apparatus is not limited to the example, and various changes and modifications can obviously be made within the range that does not deviate from the spirit of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 magnetic heat pump device     -   2 magnetic heat pump AMR     -   3 housing     -   6 permanent magnet (magnetic field changing device)     -   7 rotating body (magnetic field changing device)     -   8 displacer (heat transfer medium moving device)     -   9 cam (heat transfer medium moving device)     -   11A, 11B magnetic working body     -   12 duct     -   13 magnetic working substance     -   14 high-temperature end     -   16 low-temperature end     -   19, 22 external heat exchanger     -   21, 23 circulation pump     -   24, 26 heat exchanger     -   27 first external heat transfer medium circulation circuit     -   28 second external heat transfer medium circulation circuit     -   M motor 

1. A magnetic heat pump apparatus comprising: a magnetic working body which includes a magnetic working substance having a magnetocaloric effect and in which a heat transfer medium is circulated; a magnetic field changing device which changes the size of a magnetic field to be applied to the magnetic working substance; a displacer which reciprocates the heat transfer medium between a high-temperature end and a low-temperature end of the magnetic working body; and an external heat transfer medium circulation circuit which has an external heat exchanger and which circulates a second heat transfer medium, wherein the external heat transfer medium circulation circuit causes the second heat transfer medium and the heat transfer medium of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium that has been subjected to the heat exchange to the external heat exchanger.
 2. The magnetic heat pump apparatus according to claim 1, comprising: a first external heat transfer medium circulation circuit which has the external heat exchanger on a heat dissipation side; and a second external heat transfer medium circulation circuit which has the external heat exchanger on a heat absorption side, wherein the first external heat transfer medium circulation circuit causes the second heat transfer medium and a heat transfer medium on a high-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium which has been subjected to the heat exchange to the external heat exchanger on the heat dissipation side, and the second external heat transfer medium circulation circuit causes the second heat transfer medium and a heat transfer medium on a low-temperature end side of the magnetic working body to carry out heat exchange, and circulates the second heat transfer medium which has been subjected to the heat exchange to the external heat exchanger on the heat absorption side.
 3. The magnetic heat pump apparatus according to claim 1, comprising: a high-temperature end side displacer provided on the high-temperature end side of the magnetic working body; and a low-temperature end side displacer provided on the low-temperature end side of the magnetic working body, wherein the high-temperature end side displacer and the low-temperature end side displacer are placed back to back. 